The Milltek Sport Secondary Cat Back Exhaust System is designed for BMW E82/E88 135i models with the twin-turbocharged N54 engine . This system is an excellent solution for the driver who wants to improve the sound and exhaust flow of their car without touching the primary catalytic converters.
The Secondary Cat Back system replaces the section of the exhaust system after the secondary catalytic converters , retaining the key components of the car's emissions system but unleashing the characteristic and sporty sound of the N54 engine.
Rich and powerful N54 sound profile
Milltek has tuned this system specifically to suit the nature of the N54 engine:
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Deeper and fuller sound at idle
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Clearly stronger and more aggressive sound during acceleration
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Clean and sporty sound at high revs
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No annoying resonance or drone during normal driving
The sound profile emphasizes the N54's performance and mechanical nature while still maintaining good driving comfort.
Improved flow and ride feel
Milltek Secondary Cat Back Exhaust System:
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reduces exhaust back pressure after secondary catalytic converters
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supports engine's sensitive throttle response
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improves the overall driving experience
The freer-flowing structure also supports significant power upgrades and tuning configurations.
Easy bolt-on installation
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to fit directly into the car's original mounting points
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for installation without welding or permanent changes
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to work seamlessly with the standard front end
OEM-level fit ensures quick and clean installation.
304L Aircraft Grade Stainless Steel
The entire exhaust system is made of high-quality 304L grade stainless steel , which provides:
The choice of materials meets Milltek's high quality and durability standards.
Fit
Engine: 3.0 Twin Turbo (N54)
Model years 2008–2010